A number of new leavers (7)
I believe the answer is:
several
'a number of' is the definition.
(I've seen this in another clue)
'new leavers' is the wordplay.
'new' is an anagram indicator.
'leavers' is an anagram of 'SEVERAL'.
(Other definitions for several that I've seen before include "Assorted" , "Reveals (anag.)" , "Sundry, distinct" , "Divers" , "A few; separate" .)